Crop management and its effects on weed occurrences

The objective was to evaluate weed phytosociology and similarities between crop management systems in the Chapadões region. The experiment was conducted at in agricultural area located in the municipality of Chapadão do Sul, MS, during the 2016/17 harvest. Three crop managements strategies were used: (1) cotton/soybean/Urochloa, (2) millet/soybean/millet and (3) millet/soybean/crotalaria. A phytosociological survey of weeds was carried out during soybean cultivation and cover crops growth, in succession. The evaluation area for each management strategy was 0.5 ha. Soybean surveys were carried out in October and January, while the cover crop surveys were performed in February and May. The relative frequency (RF), relative density (RD), relative abundance (AR), and relative importance (RI) of weeds, Venn diagram, and Jaccard and Sorenson similarity indices were evaluated. The management area represented by the cotton/soybean/Urochloa rotation had fewer weed species than others. The species Cenchrus echinatus, Digitaria insularis, Digitaria sanguinalis, Eleusine indica and Commelina benghalensis had the highest phytosociological indeces among the monocotyledons. Attention is required for managing the dicotyledons Amaranthus deflexus, Conyza canadensis and Senna obtusifolia despite their low indices because of herbicide resistant cases. The highest indeces of similarity were found between managements areas 2 and 3, which did not rely on cotton cultivation prior to soybeans.

PHYSICAL SOIL ATTRIBUTES IN DIFFERENT EUCALYPTUS CROP MANAGEMENT SYSTEMS IN WESTERN MATO GROSSO, BRAZIL

Physical soil attributes in different eucalyptus crop management systems in western Mato Grosso, Brazil. The aim of this study was to determine the effect of four soil management systems on the physical attributes of an Oxisol for Eucalyptus crops in western Mato Grosso, Brazil. The management systems are differentiated by the soil preparation form during the implantation and initial forest establishment phases, namely a conventional system (plowing, harrowing and subsoiling for preparation and harrows for weed control after planting ) and a conservationist system (pasture desiccation, subsoiling, herbicide weed control and cover crop), with added differences in the eucalyptus fertilizer supply manner (haul and furrow). Nine soil layers were sampled continuously for each management system in between the sowing lines using 100 cm³ volumetric rings (0.05 m in diameter and height), totaling a studied layer of 0.45 m. The following variables were evaluated: total pore volume, microporosity, macroporosity, density and soil resistance to penetration. The different managements did not lead to significant differences for the studied attributes two years after forest establishment, with only a small depth effect observed. The attribute values are within the appropriate limits for eucalyptus crop development, indicating good soil quality under the eucalyptus forest for the study conditions.Keywords: Cover crop, Eucalyptus, soil management, soil penetration resistance.

Multiple-Disease System in Coffee: From Crop Loss Assessment to Sustainable Management

Assessment of crop loss due to multiple diseases and pests (D&P) is a necessary step in designing sustainable crop management systems. Understanding the drivers of D&P development and yield loss helps identify leverage points for crop health management. Crop loss assessment is also necessary for the quantification of D&P regulation service to identify promising systems where ecosystem service provision is optimized. In perennial crops, assessment of crop losses due to D&P is difficult, as injuries can affect yield over years. In coffee, one of the first perennials in which crop loss trials were implemented, crop losses concurrent with injuries were found to be approximately 50% lower than lagged losses that originated following the death of productive branches due to D&P. Crop losses can be assessed by field trials and surveys, where yield reduction factors such as the number of productive branches that have died are quantified, and by modeling, where damage mechanisms for each injury are considered over several years.

Performance of crispy lettuce cultivars in different soil covers

The lettuce cropping is an important segment of the national agriculture, with strong economic expression. However, climatic factors such as high temperature and humidity can affect this vegetable cultivation. These environmental conditions are common in various Brazilian regions, so the growers should adopt crop management systems, as soil covers, to minimize the environmental effect and obtain higher returns. Thus, the aim of this study was to evaluate the influence of different soil covers on the agronomic performance of crispy lettuce cultivars. The study was conducted at UNESP, Registro Campus, Brazil, from August to October, 2013. The experiment was carried out in a randomized blocks design, arranged in a 4x4 factorial, with three repetitions. The treatments consisted of the factors soil covers (black mulching, silver mulching, white mulching and control) and cultivars (Inaiá, Milena, Vanda and Vera). The experimental unit consisted of fifteen plants, with the useful area composed of nine central plants. At harvest, the following characteristics were evaluated: plant height, head diameter, fresh mass, number of leaves, leaf width, leaf height, stem diameter, heart diameter, heart height, dry mass, yield and nitrate content. Among the studied covers, white mulching showed the best results for the main productive characteristics and can be used as soil cover in the cultivation of Vera, Vanda and Inaiá culivars.